Sato Norihiro, Kobayashi Satomi, Aoki Motohide, Umemura Tomonari, Kobayashi Isao, Tsuzuki Mikio
School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo 192-0392, Japan; JST, Chiyoda-ku, Tokyo 102-0075, Japan.
School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo 192-0392, Japan.
Biochem Biophys Res Commun. 2016 Jan 29;470(1):123-129. doi: 10.1016/j.bbrc.2016.01.006. Epub 2016 Jan 6.
Sulfoquinovosyl diacylglycerol is one of the lipids that construct thylakoid membranes, and is distributed from cyanobacteria to plastids in plants including a red lineage. One of the most primitive red algae, Cyanidioschyzon melorae, similar to cyanobacteria and green plants, possesses homologs of the SQD1 and SQD2 genes that code for UDP-sulfoquinovose and sulfoquinovosyl diacylglycerol synthases, respectively, for the synthesis of sulfoquinovosyl diacylglycerol. We here revealed the structural properties of SQD1 and SQD2 homologs in C. melorae intrinsic to those of the authentic proteins, and verified their enzymatic functions through heterologous expression in cyanobacterial disruptants as to the corresponding genes. The results demonstrated that the system of sulfoquinovosyl diacylglycerol synthesis could have been conserved through evolution of cyanobacteria to plastids in a red lineage, which is compatible with the monophyletic origin of plastids.
磺基喹喔啉二酰基甘油是构成类囊体膜的脂质之一，广泛分布于从蓝细菌到包括红系植物在内的质体中。最原始的红藻之一，嗜热栖热放线菌，与蓝细菌和绿色植物相似，拥有分别编码UDP - 磺基喹喔啉和磺基喹喔啉二酰基甘油合酶的SQD1和SQD2基因的同源物，用于合成磺基喹喔啉二酰基甘油。我们在此揭示了嗜热栖热放线菌中SQD1和SQD2同源物与真实蛋白质的结构特性，并通过在蓝细菌破坏体中对相应基因的异源表达验证了它们的酶功能。结果表明，磺基喹喔啉二酰基甘油合成系统可能在从蓝细菌到红系植物质体的进化过程中得以保留，这与质体的单系起源是一致的。
